Remove the shell from the prawns. Combine all the ingredients except the prawns in a bowl and whisk to combine. Taste to ensure that the seasoning and spice is to your liking. Place the marinade into a large zip-lock bag or a bowl and add the prawns. Toss everything well so that the prawns are completely covered. If the marinade is not enough, add just a little bit of water. Do not allow the shrimp to stay in the marinade for longer than 45 minutes. Thread 2-3 prawns on each skewer. Grill for 3 minutes on the first side and 3 minutes on the second side. Serve with lime wedges and basmati rice.